Re: [PATCH 07/12] perf_events: add LBR software filter support forIntel X86

From: Stephane Eranian
Date: Fri Oct 07 2011 - 06:38:45 EST

On Thu, Oct 6, 2011 at 5:32 PM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>> + Â Â kernel_insn_init(&insn, kaddr);
>> + Â Â insn_get_opcode(&insn);
> This makes me uncomfortable. AFAIK that's the first use of the opcode
> decoder being used directly for user space. It has a quite large attack
> surface. Who says it cannot be exploited?
This is not new, it's already used for the PEBS fixups and that includes
user level fixups, if possible.

We are not executing the instruction here, just decoding it to filter it out
from a buffer if necessary.

> -Andi
> --
> ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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